The most impressive factor of this episode must be the visuals. Akhaten's "😮" form is magnificently achieved, and to be fair, most of the costumes actually look quite good, although that one that's just the Hoix with random bits shoved on its mush literally just looks like that. Also, the Vigil look excellent, and the girl who plays Merry (I don't remember her name unfortunately, but I think she's Aled Jones's daughter) is fantastic too. The episode has a warm colour palette, which works really well with the tone.
Oh, and the Doctor doing the classic "looking over the newspaper" routine, but with the Beano, is very sweet. And very Doctorly.